Chemical and Structural Studies of Antibodies and Histocompatibility Antigens. It is the purpose of this project to study the chemistry and structure of antibodies and histocompatibility antigens. Antibodies of different specificities are purified. The chemical sequence of both the light and heavy chains is obtained in order to gain some insight into the nature of antibody specificity and the generation of diversity. Isolation methods for histocompatibility antigens and tumor antigens have been worked out. The characterization of the chemical structure of these proteins is being approached by micro methods and the relationship of the amino acid sequence to immunoglobulin structure or other known structures is being analyzed. Epoxide hydrase plays a critical role in chemical-induced mutagenesis and carcinogenesis. Structural studies have been undertaken with the goal of identifying amino acid residues which are essential for catalytic function.